Advances in Schaftoside Research: Pharmacological Mechanisms, Pharmacokinetics, and Therapeutic Perspectives

Abstract

Schaftoside is a flavonoid C-glycoside widely existing in medicinal plants and has been extensively reported due to its pharmacological activities, such as anti-inflammatory, hepatoprotective, antioxidant and neuroprotective activities. These pharmacological activities may be attributed to its effects on apoptosis, autophagy, ferroptosis, pyroptosis, oxidative stress and related signaling pathways. In this review, we summarize recent advances in pharmacological activities and pharmacomechanisms of schaftoside as well as its pharmacokinetic properties, formulation strategies, safety and therapeutic application. The biological effects of schaftoside have been demonstrated in various pathological models by relevant in vitro and in vivo experiments. However, its oral bioavailability is extremely low, which is a big challenge for its further development. Some formulation approaches, especially drug delivery systems, have shown preliminary prospects, but related reports are limited. Based on available toxicological findings, schaftoside is expected to have a relatively safe profile. However, the relationship between schaftoside and chemosensitivity as well as drug resistance needs to be further investigated. In conclusion, schaftoside is a promising bioactive compound; however, its pharmacokinetic properties and available clinical evidence need to be further investigated.

Introduction

Schaftoside is a natural flavonoid glycoside compound that was first isolated by researchers from various plants, such as those in plants of the genus Arisaema,1 plants of the genus Desmodium,2,3 plants of the genus Glycyrrhiza,4 and plants of the Abrus cantoniensis Hance.5–7 The chemical structure of schaftoside is shown in Figure 1. Schaftoside consists of an apigenin core, with a C-glucosyl group attached at the C-6 position and a C-arabinosyl group attached at the C-8 position, forming stable C–C glycosidic bonds. Its systematic name is 6-C-glucosyl-8-C-arabinosyl apigenin, with a molecular formula of C₂₆H₂₈O₁₄ and a molecular weight of 564.49 g/mol. Schaftoside is a positional isomer of isoschaftoside, in which the C-glucosyl and C-arabinosyl groups are attached to the C-8 and C-6 positions of the apigenin core, respectively. Due to its unique C-glycosidic structure, schaftoside has attracted increasing research attention. It is insoluble in less polar solvents such as chloroform, petroleum ether, and diethyl ether, but is readily soluble in methanol, ethanol, and hot water.8 Schaftoside is widely found in various plant families, including the Fabaceae, Lamiaceae, Araceae, and Hypericaceae, and is a naturally occurring active flavonoid compound. Schaftoside is a natural flavonoid bioactive compound widely distributed in various plants, including those belonging to the Fabaceae, Lamiaceae, Araceae, and Hypericaceae families. It is found at relatively high concentrations in the aboveground parts of plants such as Grona styracifolia2 and exhibits diverse pharmacological activities, including anti-inflammatory, hepatoprotective, antioxidant, and neuroprotective effects.3,5,7,9 It exerts these effects primarily through various mechanisms, including the regulation of apoptosis and autophagy, the alleviation of oxidative stress, and the suppression of inflammatory responses. This review is intended to summarize the recent advances in the pharmacological effects of schaftoside in an orderly way to lay a theoretical foundation for its further research and clinical application.

Figure 1.

Structural formula of Schaftoside.

Methods

This review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The titles, abstracts, and full texts of the retrieved records were screened in a stepwise manner. A literature search was performed in Web of Science, PubMed, EMBASE, MEDLINE, and CNKI using different combinations of English and Chinese search terms, such as schaftoside, apoptosis, autophagy, pyroptosis, ferroptosis, programmed cell death, pharmacokinetics, nanocarriers, and safety. The search was conducted from database inception to September 2026. A total of 229 records were initially retrieved from the initial search.

Two researchers screened the retrieved records by reviewing their titles, abstracts, and full texts in a stepwise manner. In the event of disagreement, the two researchers discussed and reached a consensus, and if necessary, consultation with a third researcher was sought. The inclusion criteria were original research studies and clinical trials focusing on schaftoside in life sciences and other related fields. The exclusion criteria were editorials, letters, conference abstracts, review articles, duplicate publications, studies beyond the scope of this review, and studies for which the full text was unavailable. Finally, 33 studies were included after rigorous screening and eligibility assessment.

Regulation of Cell Death and Cellular Stress by Schaftoside

Schaftoside exerts its pharmacological effects through multifaceted mechanisms of cell death intervention, inhibiting apoptosis, modulating autophagy, and effectively blocking ferroptosis. Schaftoside showed substantial protection against disease progression in a wide range of pathological models, thus making it a great foundation for its broad pharmacological activity. Refer to Table 1 and Figure 2.

Table 1.

Regulation of Cell Death and Cellular Stress by Schaftoside

	Disease	Evaluation Model	Compound	Treatment Concentration	Possible Mechanisms	Reference
Apoptosis	Seizure	Zebrafish	Pure compound	100, 200, 400 μM for 24 h	Downregulates pro-inflammatory factors IL-6, IL-1β, and NF-κB; restores the activity of antioxidant enzymes CAT, GPx, and SOD; upregulates GPx1a and Mn-SOD expression; reduces oxidative stress and inflammation-induced neuronal apoptosis.	[10]
	Lung cancer	A549 Cells	Hypericum perforatum extract containing schaftoside	2.5 μg/mL for 24 h	Hypericum perforatum extract containing schaftoside induced cytotoxicity and apoptosis in A549 cells, increased G0/G1 cell-cycle arrest, and inhibited cell proliferation. The specific contribution of schaftoside remains unclear because the effects were evaluated using the whole extract	[11]
	Liver cancer	HCC Cells	Pure compound	194 μM for 24 h	Schaftoside inhibited H22 hepatocellular carcinoma cells and modulated p53/Bcl-2-related apoptotic signaling, suggesting potential pro-apoptotic activity	[12]
Autophagy	CI/RI	MCAO HT22 Cells	Pure compound	MCAO: (50/100/150 mg/kg), administered by gastric lavage 1 hour before reperfusion. HT22 Cells: OGD/R was performed 24 hours after pretreatment at concentrations of (0.1/0.5/1 μM)	Schaftoside alleviated cerebral ischemia-reperfusion injury by activating autophagy via the AMPK/mTOR pathway, as evidenced by increased p-AMPK/AMPK, LC3-II/LC3-I, and Beclin-1 levels, and decreased p-mTOR/mTOR and p62 expression	[13]
	HFpEF	AC16 cells; NMCM cells; Mouse model of HFpEF	Pure compound	Mouse model of HFpEF: 20/40 mg/kg/day (gastric administration × 4 weeks); AC16 cells/NMCM cells: pretreated with 80 ng/mL for 24 hours	Schaftoside acts as an allosteric modulator of CaMKII-δ, regulating its activity and thereby enhancing autophagy-lysosome function. It promotes autophagosome formation and upregulates the lysosomal marker LAMP1, indicating improved autophagic flux and lysosomal repair. Through modulation of CaMKII-δ-mediated autophagy regulation, schaftoside alleviates cardiac hypertrophy and fibrosis, ultimately improving diastolic function in HFpEF models	[4]
	Melanoma	B16F1 Cells	Pure compound	1 μM, for 24 hours	Induces autophagy in B16F1 melanoma cells, promoting the conversion of LC3-I to LC3-II, downregulating p62, and clearing melanin-synthesis-related enzymes—tyrosinase (TYR) and tyrosinase-related protein-1 (TRP1)—ultimately inhibiting melanin synthesis	[14]
Ferroptosis	ALI	ALI Mouse Model; Human normal liver cell line (L02 cells) induced with Erastin or CCl4	Pure compound	ALI Mouse Model: 40 mg/kg/day, administered via gavage for 7 days; Human normal liver cell line (L02 cells) induced with Erastin or CCl4: 80 μg/mL, pretreated for 24 hours.	Schaftoside alleviated acute liver injury by inhibiting ferroptosis through regulation of the CUL1–Nrf2/GPX4 axis. It enhances Nrf2 stability by potentially suppressing CUL1-mediated ubiquitination and degradation of Nrf2, thereby upregulating GPX4 expression, promoting GSH-dependent lipid peroxide clearance, and reducing Fe2⁺ accumulation and ferroptotic cell death	[15]
Pyroptosis and Inflammation	ALI	Mouse Model of Memory-Related Lung Injury	Pure compound	160 mg/kg as a single intraperitoneal injection	Binding to Drp1, it inhibits Ser616 phosphorylation, upregulates the expression of Mfn1/2 and OPA1 proteins, blocks mitochondrial fission, restores mitochondrial fusion, reduces the release of mtROS and mtDNA, and downregulates the expression of NLRP3, ASC, and Caspase-1, thereby blocking pyroptosis execution	[16]
	Aspergillus fumigatus Keratitis	HCECs stimulated by cellular hyphae.	Pure compound	160μM pretreatment in vitro for 2 hours + 8 hour stimulation.	Schaftoside alleviated Aspergillus fumigatus-induced fungal keratitis by inhibiting the TLR4/MyD88 inflammatory pathway and mitochondrial dysfunction. It reduced pro-inflammatory cytokine production (IL-1β, TNF-α, IL-6), suppressed Drp1 phosphorylation and mitochondrial fragmentation, thereby alleviating oxidative stress, inflammation, and epithelial barrier damage	[17]
	Ischemic stroke	BV2 Cells	Pure compound	0.01 mM, 0.1 mM, 1 mM (dose-dependent experiment); co-treatment with Schaftoside and OGD for 4 hours	Downregulates the expression of TLR4 and MyD88, thereby inhibiting the initiation of the TLR4/MyD88 signaling pathway; this leads to indirect suppression of Drp1 phosphorylation at Ser616, preventing Drp1 translocation to mitochondria and ultimately reducing the secretion of pro-inflammatory cytokines—including IL-1β, IL-6, and TNF-α—thereby alleviating neuroinflammation in BV2 microglial cells	[18]
Oxidative Stress	AD	Mouse Model of Scopolamine-Induced Cognitive Impairment; SH-SY5Y Cells	Pure compound	Mouse Model of Scopolamine-Induced Cognitive Impairment: Gastric administration of Schaftoside, 25/50 mg/kg for 7 days; SH-SY5Y Cells: Pretreatment with Schaftoside (100 μM) for 24 hours.	Reduced intracellular ROS levels and senescence-associated β-galactosidase (SA-β-gal) activity, while downregulating the expression of the senescence-related genes p16 and p21 and upregulating SIRT1 expression. In addition, the study suggested that schaftoside may possess potential blood–brain barrier permeability.	[19]

Figure 2.

Regulation of Cell Death Pathways by Schaftoside.

Apoptosis

Apoptosis plays a vital role in physiological tissue remodeling and in maintaining the dynamic balance of cellular population homeostasis by activating specific caspase cascades.20 Schaftoside has been able to protect the tissues quite effectively by blocking apoptosis in a number of disease situations, such as neurological disorders, cancers, and tissue damage.

In terms of neuroprotection, a study by Dang et al10 showed that, following pretreatment with schaftoside, the pro-inflammatory factors interleukin-6 (IL-6), interleukin-1β (IL-1β), and nuclear factor kappa B (NF-κB) were significantly downregulated in a pentylenetetrazol (PTZ)-induced zebrafish seizure model, reducing the recruitment of immune cells and thereby blocking the inflammation-induced apoptosis pathway; At the same time, schaftoside pretreatment restored the activity of the antioxidant enzymes catalase (CAT), glutathione peroxidase (GPx), and superoxide dismutase (SOD) that had been suppressed by PTZ, upregulated the mRNA levels of GPx1a and Mn-SOD, and reduced oxidative stress-induced damage. Therefore, schaftoside effectively reduces PTZ-induced neuronal apoptosis by synergistically inhibiting inflammatory responses and oxidative stress. Güzel et al11 investigated the anticancer activity of a Hypericum perforatum extract in several cancer cell lines, including A549 lung carcinoma cells. LC-MS/MS analysis identified schaftoside as one of the constituents present in the extract. In vitro experiments demonstrated that the extract exerted marked cytotoxic and pro-apoptotic effects on A549 cells, with the apoptotic rate reaching 53.67%. Flow cytometric analysis showed that the proportion of cells arrested at the G0/G1 phase was greatly increased (76.37%), while the population of cells in the S and G2/M phases were greatly decreased. Therefore, our results indicated that Hypericum perforatum extract may inhibit the proliferation of A549 cells by inducing G0/G1 cell-cycle arrest. However, because we used the whole extract instead of schaftoside to investigate the anticancer and cell-cycle regulatory effects, it was unclear whether schaftoside was responsible for these effects, and further research is needed.

Bcl-2 family proteins are central regulators of apoptosis. Normally, Bcl-2 family proteins are maintained in a balance state with the pro-apoptotic protein Bax; when cells are in a pathological state, the expression of Bcl-2 is down-regulated while the expression of Bax is up-regulated, and then the apoptotic pathway is activated.21 Huang et al12 integrated network pharmacology, molecular docking, and in vitro experiments to study the potential anticancer effect of schaftoside, which was previously identified from Gansu Banxia Decoction (GSBXD). The results showed that schaftoside had a significant inhibitory effect on H22 hepatocellular carcinoma cells and increased the expression of p53 while reducing the expression of Bcl-2. Given the established involvement of p53 and Bcl-2 in the regulation of apoptosis, these findings suggest that the anticancer activity of schaftoside may be associated with modulation of the p53/Bcl-2-related apoptotic process.

Autophagy

Autophagy, as a highly conserved degradation mechanism, plays a central regulatory role in clearing damaged organelles and misfolded proteins and maintaining intracellular homeostasis.22 By activating or regulating autophagy pathways, schaftoside exerts key biologically active effects in pathophysiological processes such as neuroprotection, cardiovascular disease intervention and the inhibition of melanin synthesis.

Zhang et al13 found that schaftoside significantly alleviated neurofunctional deficits and cerebral edema caused by cerebral ischemia-reperfusion (CI/RI) in both in vitro and in vivo models. Further studies revealed that schaftoside upregulates the expression of p-AMPK/AMPK and downregulates the p-mTOR/mTOR ratio; simultaneously, schaftoside upregulates the expression of the classic autophagy proteins LC3-II/LC3-I and Beclin-1, while downregulating the expression of p62. In the CI/RI model prepared from HT22 cells in vitro, it was verified that the results were consistent with those in vivo. The addition of an autophagy inhibitor reversed the protective effects of schaftoside. This strongly demonstrates that schaftoside exerts its protective effects in CI/RI by upregulating autophagy levels through the AMPK/mTOR pathway. Zhang et al4 demonstrated that schaftoside alleviated heart failure with preserved ejection fraction (HFpEF) by targeting calcium/calmodulin-dependent protein kinase II (CaMKII)-δ and regulating autophagy. Biophysical and functional studies suggested that schaftoside directly interacted with CaMKII-δ, with surface plasmon resonance (SPR) analysis showing a binding affinity (K_D = 0.14 mmol/L) and enzyme inhibition assays demonstrating inhibitory activity (IC₅₀ = 0.21 μmol/L). Mutational analysis of CaMKII-δ (S333A/T336A mutants) further supported the functional relevance of this interaction, while molecular docking and dynamics simulations suggested an allosteric binding mode involving the ATP-binding region. However, stoichiometric characterization and cellular target engagement validation (eg, CETSA) are still absent. Functionally, schaftoside intervention elevated the expression level of lysosomal marker LAMP1 and enhanced the function of autophagosome formation in an Ang II–induced HFpEF model. Furthermore, the above changes were associated with the improvement of diastolic function and the alleviation of myocardial hypertrophy and fibrosis. Kim et al14 concluded that schaftoside induces autophagy in B16F1 melanoma cells, enhances the conversion of LC3-I to LC3-II, downregulates p62, and diminishes the aggregation of melanin-synthesis related enzymes, tyrosinase (TYR) and tyrosinase-related protein-1 (TRP1), finally inhibiting the synthesis of melanin.

However, it is worth noting that, these phenomena were observed at various concentrations and in different models, and the evidence is still scarce Therefore, whether autophagy modulation is a general property of schaftoside and whether this effect varies depending on the tissue and experimental context remain to be determined.

Ferroptosis

Ferroptosis is iron-dependent, lipid peroxidation-driven cell death. Its core molecular mechanism involves an imbalance in intracellular iron homeostasis and impaired function of the antioxidant system mediated by glutathione peroxidase 4 (GPX4), leading to a cascade of peroxidation of polyunsaturated fatty acids (PUFAs) in the phospholipid bilayer, which ultimately disrupts membrane structural integrity and induces non-apoptotic cell death.23 Schaftoside has significantly inhibited ferroptosis, notably in models of kidney and liver.

Yu et al15 reported that schaftoside alleviated acute liver injury (ALI) by inhibiting ferroptosis. Based on network pharmacology analysis and molecular docking, CUL1 was predicted as a potential target of schaftoside. The authors proposed that schaftoside may regulate the CUL1–Nrf2 axis by affecting CUL1-mediated ubiquitination and degradation of Nrf2, thereby enhancing Nrf2 stability and increasing GPX4 expression. Activation of the Nrf2/GPX4 pathway was associated with enhanced GSH-dependent elimination of lipid peroxides and suppression of ferroptotic cell death. In ALI models, schaftoside treatment reduced hepatic MDA and Fe²⁺ accumulation and modulated ferroptosis-related markers, including COX2 and ALOX12/15. Furthermore, molecular docking analysis suggested potential interactions between schaftoside and several ferroptosis-related proteins, including ALOX12, SOD2, HAO1, and GCH1. However, these computationally predicted interactions, including the proposed association with CUL1, require further experimental validation using direct target engagement approaches.

These findings confirm that schaftoside reduces ROS production by inhibiting ALOX12 and HAO1, while simultaneously enhancing the activity of SOD2 and GCH1 to strengthen antioxidant defense. In summary, by targeting the CUL1-Nrf2-GPX4 pathway, schaftoside simultaneously regulates three key processes—oxidative stress, iron metabolism disorders, and mitochondrial dysfunction—to inhibit the ferroptosis process from multiple dimensions, thereby effectively alleviating ALI.

Pyroptosis and Inflammation

The initiation of pyroptosis is closely associated with the activation of the NLRP3 inflammasome, while oxidative stress and mitochondrial dysfunction are key drivers of inflammasome activation.24 Chen et al16 found that schaftoside, by specifically binding to Drp1, inhibits Ser616 phosphorylation, upregulates the expression of Mfn1/2 and OPA1 proteins, blocks mitochondrial fission, restores mitochondrial fusion, reduces mtROS/mtDNA release, and downregulates the expression of NLRP3, ASC, and Caspase-1, thereby blocking pyroptosis and ultimately improving acute lung injury. Lu et al17 reported that schaftoside alleviated Aspergillus fumigatus-induced corneal inflammation in human corneal epithelial cells (HCECs). Schaftoside inhibited the Toll-like receptor 4 (TLR4)/myeloid differentiation primary response 88 (MyD88) inflammatory signaling pathway, reduced the production of pro-inflammatory cytokines (IL-1β, TNF-α, and IL-6), and suppressed Drp1 phosphorylation and mitochondrial fragmentation, thereby improving oxidative stress, inflammation, and epithelial barrier damage. These findings suggest that schaftoside has protective effects against fungal keratitis by modulating inflammatory responses and mitochondrial dysfunction. Zhou et al18 found that when schaftoside was administered to BV2 cells subjected to oxygen-glucose deprivation, TLR4 and MyD88 expression was downregulated, inhibiting the initiation of the TLR4/MyD88 signaling pathway and indirectly blocking the activation of Drp1 (Ser⁶¹⁶), thereby preventing the translocation of Drp1 to the mitochondria and ultimately reducing the release of pro-inflammatory factors (IL-1β, IL-6, TNF-α), thereby alleviating neuroinflammation in BV2 cells.

The above studies indicate that schaftoside exerts its pharmacological effects through multidimensional cell death mechanisms, including apoptosis, autophagy, ferroptosis, and pyroptosis, thereby providing evidence for the basis of schaftoside’s pharmacological activity.

Oxidative Stress

Sie et al19 investigated the effects of schaftoside on D-galactose-induced senescence in SH-SY5Y neuronal cells. Treatment with schaftoside improved cell viability, reduced intracellular ROS levels and senescence-associated β-galactosidase (SA-β-gal) activity, while decreasing the expression of the senescence-related genes p16 and p21 and increasing sirtuin 1 (SIRT1) expression. In addition, the study suggested that schaftoside may possess potential blood–brain barrier permeability, supporting its possible application in the central nervous system. Overall, our results suggest that schaftoside may suppress the senescence and protect neurons by ameliorating oxidative stress and modulating SIRT1 signaling pathway.

It should be remarked that the regulation of cell fate by schaftoside seems to be context dependent. In normal tissues, schaftoside seems to exert antioxidant and cytoprotective effects likely through the amelioration of oxidative stress and inflammation. In contrast, in tumor cells, schaftoside may induce cell death via mitochondrial dysfunction and the activation of related apoptosis signaling pathways, which may be mediated by the cancer cell-specific redox balance and apoptosis sensitivity. The above mentioned circumstances may result in the difference in drug concentration, cellular redox status and experimental models. However, the present evidence is still insufficient to confirm whether hormesis may be an universal mechanism for the two different biological effects induced by schaftoside.

Pharmacokinetics and Formulation Strategies

Schaftoside pharmacokinetic property is important for the clinical application perspective and the formulation strategy could be used to overcome the pharmacological property related to poor bioavailability. See Table 2.

Table 2.

Pharmacokinetics for Schaftoside

	ADME	Source	Type	Results	Reference
Pharmacokinetics	Absorption	Pure compound	Measured Values	The half-life is 0.58 hours. It is rapidly absorbed following oral administration (reaching Cmax in 0.67–1.17 hours), but oral bioavailability is low, ranging from only 0.42% to 0.71% at doses of 5–20 mg/kg	[25]
	Absorption	Pure compound	Measured Values	The absolute bioavailability of schaftoside was also confirmed to be 0.95% using the UPLC-MS/MS method	[26]
	Absorption	Pure compound	Model-based Predictions	A biphasic pharmacokinetic model was proposed, suggesting that schaftoside may be absorbed at two different sites in the intestine	[27]
	Distribution	Pure compound	Measured Values	Using the HPLC-ESI-MS method, data were obtained to support the tissue distribution of schaftoside in the body	[28]
	Distribution	Pure compound	Measured Values	The protein binding of schaftoside in rat and human plasma was determined using the rapid equilibrium dialysis method. Schaftoside exhibited moderate protein binding (56.6–61.5% in rat plasma and 55.0–62.9% in human plasma), indicating that a portion of the drug is freely distributed to tissues where it exerts its effects	[29]
	Metabolism and Excretion	Pure compound	Measured Values	No Phase I or Phase II metabolites of schaftoside were detected, indicating that its metabolism in the liver is limited; this is consistent with the characteristic of C-glycosides, which typically exhibit high metabolic stability	[30]
	Metabolism and Excretion	Pure compound	Measured Values	The metabolism of schaftoside in healthy rats and rats with calcium oxalate kidney stones was compared using the UHPLC-Q-TOF-MS/MS method, suggesting that the metabolism and excretion of schaftoside may be altered under pathological conditions	[31]
	Other	Extract of TFDS containing schaftoside	Measured Values	A comparison of the pharmacokinetics of schaftoside in normal rats and rats with urinary tract stones revealed that plasma drug levels were significantly elevated in the pathological condition.	[32]
	Other	Extract of TFRA containing schaftoside	Measured Values	Microemulsion enhanced the transdermal delivery of schaftoside, increasing its transdermal flux by 3.72-fold compared with an aqueous suspension, suggesting improved skin penetration and topical. delivery.	[8]

Pharmacokinetic Analysis

Pharmacokinetics (PK) is the study of the absorption, distribution, metabolism and excretion (ADME) of a compound schaftoside are used as an important tool to determine the clinical safety, effectiveness and dosing strategies.

Schaftoside physicochemical property may lead to its poor oral absorption. According to currently available database and PBPK-modeling data, schaftoside has a molecular weight of 564.5 g/mol, a predicted XlogP of approximately −2.2 to −2.43, a predicted acidic pKa of 6.35, an estimated aqueous solubility of 0.02 g/L at pH 7, a topological polar surface area (TPSA) of approximately 247 Ų, and 10 hydrogen-bond donors and 14 hydrogen-bond acceptors.33,34 These values should be regarded as calculated or database-derived rather than experimentally measured physicochemical parameters. Consistent with these highly polar characteristics and low predicted lipophilicity, experimental studies using Caco-2 monolayers and rat intestinal perfusion models have demonstrated limited intestinal permeability and absorption of schaftoside, with its transport involving passive diffusion and transporter-mediated processes.35 Furthermore, a pharmacokinetic study in rats demonstrated an extremely low absolute oral bioavailability of schaftoside (0.42–0.71%), despite relatively rapid absorption after oral administration.25 A subsequent study independently reported an absolute oral bioavailability of approximately 0.95% in rats, further supporting its poor systemic exposure following oral administration.26 Taken together, the high polarity, extensive hydrogen-bonding capacity, and low lipophilicity of schaftoside may restrict passive membrane permeation, while transporter-mediated processes may further limit its intestinal absorption. Therefore, the very low oral bioavailability of schaftoside is likely attributable primarily to limited intestinal absorption and permeability rather than extensive hepatic first-pass metabolism. However, because experimentally determined aqueous solubility and standardized permeability data remain insufficient, a definitive Biopharmaceutics Classification System (BCS) or Biopharmaceutics Drug Disposition Classification System (BDDCS) classification of schaftoside cannot currently be established.

In parallel, Xiong et al27 evaluated the pharmacokinetics and tissue distribution of various flavonoid C-glycoside molecules, including schaftoside, after a rat model was treated with the abrus mollis extract orally. Based on their findings, they suggested a double-peaked PK model. They believe that uptake could take place at two different segments in the bowel which, from this angle, offers a more comprehensive view of the mechanism of absorption through gut.

Regarding the distribution of schaftoside, Wang et al28 developed an HPLC-ESI-MS method to determine the levels of schaftoside in mice following oral administration of Schisandra chinensis extract, providing data on its in vivo distribution in six biological matrices: plasma, heart, liver, spleen, lung, and kidney. Ding et al29 used rapid equilibrium dialysis to determine the plasma protein binding of purified schaftoside and four other C-glycosyl flavones in rat and human plasma. Schaftoside showed moderate plasma protein binding, with binding rates of 56.6–61.5% in rat plasma and 55.0–62.9% in human plasma. These results indicate that a considerable proportion of schaftoside remains unbound in plasma, which may influence its distribution and pharmacological activity in vivo.

Regarding metabolism and excretion, Tremmel et al30 investigated the in vitro hepatic metabolism of six flavonoid C-glycosides derived from passionflower, violet, and hawthorn. Their results showed that no apparent phase I or phase II metabolites of schaftoside were detected in human liver microsomes or S9 fractions, suggesting that schaftoside exhibits high stability in hepatic metabolic systems in vitro with limited hepatic biotransformation. This finding is consistent with the relatively high structural stability generally observed in flavonoid C-glycosides. However, this study mainly focused on hepatic metabolism and did not evaluate the gut microbiota-mediated cleavage of the C-glycosidic bond or its potential contribution to the in vivo transformation of schaftoside. Liu et al31 compared the metabolism of schaftoside in healthy rats and rats with calcium oxalate kidney stones using UHPLC-Q-TOF-MS/MS. They identified 28 metabolites in healthy rats and 30 metabolites in the model rats, suggesting that the metabolism and excretion of schaftoside may be altered under pathological conditions.

Progress has also been made in pharmacokinetic studies of special populations and patients with pathological conditions. Li et al34 developed a physiologically based pharmacokinetic (PBPK) model to characterize the pharmacokinetics of schaftoside in different populations. The simulations showed that plasma exposure to schaftoside was markedly increased in patients with impaired renal function. The maximum steady-state plasma concentrations in patients with chronic kidney disease (CKD) stages 3, 4, and 5 were 3.41-, 12.32-, and 23.77-fold higher, respectively, than those observed in healthy individuals. These results suggested that a relatively large amount of schaftoside was still existed as unbound drug in plasma, and might affect its distribution and pharmacological effects in vivo.

These results demonstrated that schaftoside might be accumulated in the body as renal function declined. Therefore, the safety of enhanced exposure should be considered when total flavonoid extracts containing schaftoside were administered to renal impairment patients. Li et al32 also investigated the pharmacokinetics of schaftoside in normal rats and rats with urinary tract stones. They found that plasma schaftoside concentrations were significantly higher in rats with urinary tract stones, which indicated that the disease status might affect schaftoside pharmacokinetics in vivo.

In summary, pharmacokinetic studies in available references could elucidate the absorption, distribution, metabolism, and excretion (ADME) profiles of schaftoside, and characterized several pharmacokinetic features of schaftoside. Rapid absorption and elimination, an absolute oral bioavailability lower than 1%, was exhibited by schaftoside. The fact that schaftoside displayed a biphasic absorption model might indicate that schaftoside could undergo multiple absorption processes in gastrointestinal tract, and moderate plasma protein binding might help schaftoside distribution to target tissues. In addition, schaftoside showed relatively high metabolic stability in liver, and schaftoside could hardly undergo Phase I or Phase II metabolic transformation process based on the available data. The special C-glycosidic structure of schaftoside might be the reason for its metabolic stability. However, disease related conditions, such as urinary tract stones and renal impairment, would considerably change schaftoside exposure and elimination process, and possibly lead to enhanced drug accumulation. Especially, PBPK modeling demonstrated substantially increased schaftoside exposure and accumulation in patients with renal impairment, and careful consideration for dose selection in renal impairment patients might be required.

These pharmacokinetic characteristics could describe the in vivo disposition of schaftoside, and provided useful pharmacokinetic parameters for further drug researches. For instance, useful information could be provided for the further study on improving schaftoside oral bioavailability by nanodelivery systems and permeability enhancers, and useful information could be provided for dosing regimen design in specific pathological conditions.

Formulation Approaches

In the area of drug research, nanotechnology has been widely used to solve problems for the clinical application of bioactive molecules. Due to the high polarity and poor membrane permeability of many natural products, their oral bioavailability is very low. Thus, in order to improve their pharmacokinetic properties while making their clinical application feasible, an intelligent delivery system should be designed.

Shen et al8 studied a microemulsion based transdermal delivery system of total flavones of Rhizoma Arisaematis (TFRA), and schaftoside as one of its main active ingredients. After optimization, the transdermal flux of schaftoside in microemulsion was significantly improved compared with that of its aqueous suspension. The transdermal flux of schaftoside was 3.72-folds higher than that of the aqueous suspension. The results indicated that, as nanoscale dispersion system, microemulsion could increase the penetration of schaftoside through the skin and further improved the topical bioavailability of schaftoside. Microemulsion is quite different from conventional nanoparticle based delivery systems. Although it could not directly be used in clinical applications, its ability to increase drug permeation through the skin provided valuable information for the design of topical or transdermal delivery system of schaftoside. Thonthula et al36 reported that Viola yedoensis extract could improve skin barrier function and skin hydration, and schaftoside might be one of the bioactive ingredients responsible for skin barrier function and skin hydration. It is conceivable that schaftoside may have skin protectant activity. If we combine schaftoside and nanocarrier based delivery system, we may open a new window to improve schaftoside topical delivery and expand its potential dermatological applications.

As shown above, these properties clearly indicate that nanocarrier may help to achieve schaftoside. If we design the carrier, we may better harness the power of schaftoside and broaden its clinical applications. However, the availability of studies on the delivery of schaftoside is very low at this stage so, in order to enable schaftoside to be used in various therapeutic areas, it is essential to carry out development of carriers suitable for delivery of schaftoside.

Safety and Therapeutic Potential of Schaftoside

Schaftoside, a natural flavonoid glycoside, has been reported to exert pharmacological effects that may enhance the efficacy of conventional drugs or optimize therapeutic outcomes, in addition to its anti-inflammatory and antioxidant activities. In particular, schaftoside may contribute to reducing drug-induced toxicity, reversing drug resistance, and increasing the sensitivity of diseased cells or tissues to pharmacological treatments. These properties suggest that schaftoside may have potential as an adjunctive agent in combination therapies.

Safety and Toxicological Evaluation of Schaftoside

Some researches have experimentally tested and demonstrated the non-toxic character of schaftoside. In one study on schaftoside for a therapy of coronavirus disease 2019 (Covid-19), Yi et. al37 proved that the compound is quite safe at therapeutic doses. They found that after 7 days oral toxicity study in mice (20–300 mg/kg), there was no fatality or weight changes. Histopathological examination of several organs such as heart, liver, spleen, lungs, and kidneys also did not show any signs of pathological changes. Therefore, schaftoside is safe to be used at pharmacological concentrations and it might be an effective candidate drug for treatment of the virus. Ahmmed et al38 evaluated the safety profile of schaftoside using in-silico toxicity prediction. Schaftoside was predicted to have an LD50 of 832 mg/kg and was classified as toxicity class 4. It was predicted to be inactive for cytotoxicity, carcinogenicity, hepatotoxicity, mutagenicity, and neurotoxicity, although potential immunotoxicity was predicted. Similarly, Vijayan et al39 performed an in-silico toxicity assessment and predicted no apparent toxicity for schaftoside, suggesting a favorable preliminary safety profile and supporting its potential for further investigation. In addition, Ahmmed et al38 reported promising antiemetic activity of schaftoside in an in vivo model. However, the toxicity-related findings reported by both studies were based exclusively on computational predictions rather than experimental toxicological evaluation. Therefore, these results should be considered preliminary and require further validation through appropriate in vitro and in vivo toxicological studies.

Chemosensitivity and Drug Resistance

Fang et al40 investigated the structural characteristics of flavonoids as potential substrates of multidrug resistance-associated protein 2 (MRP2), an important drug efflux transporter involved in multidrug resistance. Schaftoside was identified as a potential MRP2 substrate based on structural affinity analysis of flavonoids. Liu et al41 found that schaftoside may enhance the sensitivity of cancer cells to chemotherapeutic agents through two mechanisms. First, schaftoside may inhibit drug efflux by downregulating the expression of drug efflux pumps such as P-glycoprotein (P-gp) on the cancer cell membrane, thereby reducing the active efflux of chemotherapeutic agents, such as doxorubicin, and maintaining intracellular drug accumulation. Second, schaftoside may interfere with DNA damage repair by inhibiting pro-survival signaling pathways such as PI3K/AKT and NF-κB, thereby weakening the ability of cancer cells to repair DNA damage and promoting chemotherapy-induced apoptosis. Lin et al42 found that schaftoside downregulates TLR4 receptor expression, inhibits NF-κB nuclear translocation, reduces the expression of downstream inflammatory cytokines TNF-α, IL-1β, and IL-6, blocks inflammatory cascades, and improves MCD-diet-induced non-alcoholic steatohepatitis (NASH). Collectively, these findings suggest that schaftoside may be relevant to mechanisms associated with drug resistance, chemotherapeutic sensitivity, and inflammatory regulation.

Nevertheless, the current evidence is insufficient to establish a synergistic interaction between schaftoside and chemotherapeutic agents. To date, no combination-index, isobologram, or in vivo combination studies have been reported, and further investigations are needed to determine whether schaftoside can genuinely enhance the efficacy of conventional chemotherapeutic agents or overcome drug resistance.

Conclusion

Schaftoside is a natural flavonoid glycoside, present in several plant parts. Over the years much research has been carried out to understand the various mechanisms of actions of this bioactive compound. This study gives an overview of the most significant results obtained regarding the various roles of schaftoside in controlling cell processes (apoptosis, autophagy, ferroptosis, pyroptosis), reduction of inflammatory responses, and its use in drug delivery systems and pharmacokinetics. The authors’ results indicate the existence of different molecular targets through which schaftoside exerts its pharmacological effects of broad range. From the point of view of drug delivery, apart from microemulsions that are nanosize carriers and increase the skin penetration of drug molecules and therefore the availability to the site of action,8 other carrier systems are also investigated for the development of formulations.

Pharmacokinetic studies results revealed that schaftoside is rapidly absorbed after oral administration but has low bioavailability; the drug is largely distributed within the body, it is minimally metabolized in liver, and the blood drug concentration may be significantly increased when certain pathologies such as renal impairments are present.28,29 The above availability information is of great importance for the dosing strategy and the safety evaluation. Moreover, the findings in the present study indicated that schaftoside is relatively non-toxic and has good safety profile.37–39 It might be that schaftoside, instead, can increase the sensitivity to other drugs or reduce their toxicity. This is suggested by the common mechanisms of action of schaftoside for different pathways of inflammation, oxidative stress, cell death and drug transporters’ interaction (eg, MRP2).40

Despite the above extensive studies on pharmacological effects of schaftoside many questions are still left open. Future research directions: First: Studies on synergy of multiple targets: Although we have already identified several different mechanisms of pharmacological actions of schaftoside, the cross-talk between these two processes (synergy or antagonism?), and how schaftoside generally regulate complex diseases remain to be elucidated in further research. Second: further investigation of pharmacological and toxicological effects of schaftoside are warranted. Although the existence of potential pharmacological activities of schaftoside has been suggested by current available reports, limited systematic studies on pharmacodynamic effects and toxicology are available. Further well-designed in vitro and in vivo preclinical studies should be performed to validate its pharmacological activities, investigate the dose-response relationships and underlying mechanisms, and comprehensively evaluate its toxicological effects. The preclinical data will be very important for deciding whether this natural flavonoid glycoside can advance to clinical development, which should eventually be supported by well-designed human clinical trials to validate its efficacy and toxicology. Third: There are still certain limitations in translating mechanisms obtained in vitro into efficacy. Since Schaftosid has a very low oral bioavailability (<1%) and is rapidly cleared, most of the related literature reported could not provide enough pharmacokinetic data to prove that the free plasma Cmax in vivo reaches the in vitro effective concentration. It is urgently needed to integrate PK-PD models with novel nanodelivery system to bridge the gap of efficacy.

In conclusion, this natural flavonoid glycoside of schaftoside with multiple therapeutic potentials is promising for further research with modulating inflammation pathways, free radicals, brain function, liver protection, lowering levels of lipids, and even inducing death of cells etc. as the effects of anti-inflammatory, antioxidant, neuroprotective, hepatoprotective, lipid-lowering, and cell death-regulatory functions. Through an exploration of the various pharmacological mechanisms of this plant compound and the potential application of novel drug delivery techniques, schaftoside appears to be a mechanistically interesting lead compound with potential therapeutic value, although its further development as a therapeutic agent remains to be established.

Abbreviations

AD, Alzheimer’s disease; ADME, absorption, distribution, metabolism, and excretion; ALI, acute liver injury; ALOX12, arachidonate 12-lipoxygenase; AMPK, AMP-activated protein kinase; ASC, apoptosis-associated speck-like protein containing a CARD; Bax, BCL2-associated X protein; Bcl-2, B-cell lymphoma 2; BCS, Biopharmaceutics Classification System; BDDCS, Biopharmaceutics Drug Disposition Classification System; CaMKII, calcium/calmodulin-dependent protein kinase II; CETSA, cellular thermal shift assay; CI/RI, cerebral ischemia/reperfusion injury; CUL1, cullin 1; Drp1, dynamin-related protein 1; GCH1, GTP cyclohydrolase 1; GPX4, glutathione peroxidase 4; GSH, glutathione; GSBXD, Gansu Banxia Decoction; HAO1, hydroxyacid oxidase 1; HCC, hepatocellular carcinoma; HCEC(s), human corneal epithelial cell(s); HFpEF, heart failure with preserved ejection fraction; HPLC-ESI-MS, high-performance liquid chromatography-electrospray ionization-mass spectrometry; IC₅₀, half-maximal inhibitory concentration; IL, interleukin; K_D, dissociation constant; LC3, microtubule-associated protein 1 light chain 3; LAMP1, lysosomal-associated membrane protein 1; MCAO, middle cerebral artery occlusion; MCD, methionine- and choline-deficient; MDA, malondialdehyde; Mfn1/2, mitofusin 1/2; MRP2, multidrug resistance-associated protein 2; MyD88, myeloid differentiation primary response 88; NASH, nonalcoholic steatohepatitis; NLRP3, NOD-, LRR-, and pyrin domain-containing protein 3; NF-κB, nuclear factor kappa B; Nrf2, nuclear factor erythroid 2-related factor 2; OPA1, optic atrophy 1; PBPK, physiologically based pharmacokinetic; P-gp, P-glycoprotein; PI3K/AKT, phosphoinositide 3-kinase/protein kinase B; PK, pharmacokinetics; PK-PD, pharmacokinetic-pharmacodynamic; PTZ, pentylenetetrazol; PUFA(s), polyunsaturated fatty acid(s); Q-TOF, quadrupole time-of-flight; ROS, reactive oxygen species; SA-β-gal, senescence-associated β-galactosidase; SIRT1, sirtuin 1; SOD, superoxide dismutase; SOD2, superoxide dismutase 2; SPR, surface plasmon resonance; TFDS, total flavonoids of Desmodium styracifolium; TFRA, total flavones of Rhizoma Arisaematis; TLR4, Toll-like receptor 4; TNF, tumor necrosis factor; TPSA, topological polar surface area; TRP1, tyrosinase-related protein 1; TYR, tyrosinase; UHPLC, ultra-high-performance liquid chromatography; UHPLC-Q-TOF-MS/MS, ultra-high-performance liquid chromatography-quadrupole time-of-flight tandem mass spectrometry; UPLC, ultra-performance liquid chromatography; UPLC-MS/MS, ultra-performance liquid chromatography-tandem mass spectrometry.

Author Contributions

All authors made a significant contribution to the work reported, whether that is in the conception, study design, execution, acquisition of data, analysis and interpretation, or in all these areas; took part in drafting, revising or critically reviewing the article; gave final approval of the version to be published; have agreed on the journal to which the article has been submitted; and agree to be accountable for all aspects of the work.

Disclosure

The authors have declared that they have no competing interests.